Protein synthesis is a fundamental activity of all cells. It is known to place very large demands on the energy and material resources of the cell. It is likely that even minor defects in this activity would be very detrimental to cellular functions. Besides its direct importance to human cells, a full understanding of protein synthesis will be vital in the near future for the preparation of inexpensive protein pharmaceuticals. The long-tem goal of this research is to understand how the cellular components that conduct protein synthesis interact to ensure that this activity is carried out accurately and efficiently. One of the specific aims during this project period is to show how the structure of mRNA and tRNA affect these properties. Another aim is to elucidate the mechanism through which aa-tRNAs are selected by the ribosome. The investigations are to be conducted using kinetic techniques to understand how the molecules involved in protein synthesis interact in vitro. Using a rapid mixing apparatus and highly purified components, the rate at which products are made will be determined. These rates will give important information about the way the various components of the protein synthesis apparatus interact. From a knowledge of the concentrations of these components in the cell it will be possible to reconstruct events that occur inside the cell that are not accessible to direct observation.